62,984 research outputs found
Application of inflated structures to hovercraft annual survey 1968-69: inflated structures report C1206/3
1.0 Introduction
This report surveys work carried out in the Department of Aircraft
Design at the College of Aeronautics, Cranfield, in accordance with the
terms of Ministry of Technology contract reference PD/28/045/ADM, College
of Aeronautics reference 0.1206. The period covered by this report
extends from 1st October 1968 to 1st October 1969, which constitutes
the first complete year of operation under the contract terms.
The reporting procedure agreed with Mintech is that individual research
topics shall be separately reported in the form of technical memoranda,
and that comprehensive surveys of a descriptive nature shall be submitted
at regular intervals
Joining forces: engineering and arts students get physic(al) – problem solving strategies in the trans-school project
This paper / web article describes the practical investigations undertaken as part of the arts/engineering trans-school project.University of the Arts, London and Brunel University LTDU (APDU
Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission
We investigate the evolution of both the radio-loud fraction (RLF) and (using
stacking analysis) the mean radio-loudness of quasars. We consider how these
values evolve as a function of redshift and luminosity, black hole (BH) mass
and accretion rate, and parameters related to the dominance of a wind in the
broad emission line region. We match the FIRST source catalog to samples of
luminous quasars (both spectroscopic and photometric), primarily from the Sloan
Digital Sky Survey. After accounting for catastrophic errors in BH mass
estimates at high-redshift, we find that both the RLF and the mean radio
luminosity increase for increasing BH mass and decreasing accretion rate.
Similarly both the RLF and mean radio loudness increase for quasars which are
argued to have weaker radiation line driven wind components of the broad
emission line region. In agreement with past work, we find that the RLF
increases with increasing luminosity and decreasing redshift while the mean
radio-loudness evolves in the exact opposite manner. This difference in
behavior between the mean radio-loudness and the RLF in L-z may indicate
selection effects that bias our understanding of the evolution of the RLF;
deeper surveys in the optical and radio are needed to resolve this discrepancy.
Finally, we argue that radio-loud (RL) and radio-quiet (RQ) quasars may be
parallel sequences but where only RQ quasars at one extreme of the distribution
are likely to become RL, possibly through slight differences in spin and/or
merger history.Comment: 55 pages, 28 figures, accepted to A
Target shape dependence in a simple model of receptor-mediated endocytosis and phagocytosis
Phagocytosis and receptor-mediated endocytosis are vitally important particle
uptake mechanisms in many cell types, ranging from single-cell organisms to
immune cells. In both processes, engulfment by the cell depends critically on
both particle shape and orientation. However, most previous theoretical work
has focused only on spherical particles and hence disregards the wide-ranging
particle shapes occurring in nature, such as those of bacteria. Here, by
implementing a simple model in one and two dimensions, we compare and contrast
receptor-mediated endocytosis and phagocytosis for a range of biologically
relevant shapes, including spheres, ellipsoids, capped cylinders, and
hourglasses. We find a whole range of different engulfment behaviors with some
ellipsoids engulfing faster than spheres, and that phagocytosis is able to
engulf a greater range of target shapes than other types of endocytosis.
Further, the 2D model can explain why some nonspherical particles engulf
fastest (not at all) when presented to the membrane tip-first (lying flat). Our
work reveals how some bacteria may avoid being internalized simply because of
their shape, and suggests shapes for optimal drug delivery.Comment: 18 pages, 5 figure
Structure-function relations in phosphorylcholine-binding mouse myeloma proteins
The binding site interactions between the phosphorylcholine (phosphocholine)-binding mouse myeloma proteins TEPC 15, W3207, McPC 603, MOPC 167, and MOPC 511 and the isotopically substituted hapten phosphoryl-[methyl-13C]choline have been investigated using 13C and 31P nuclear magnetic resonance (NMR) spectroscopy. Each protein exhibits a unique NMR pattern, but extensive similarities in chemical shift parameters upon binding of hapten to immunoglobulin suggest a significant degree of conservation of important hapten-binding site interactions. Moreover, independent binding studies, in conjunction with the NMR data, allow construction of a simple model of the binding sites of these antibodies, analyzed in terms of the relative strength of interaction between hapten and two main subsites. The NMR evidence supports the view that the heavy chains of these proteins dominate in interacting with bound phosphorylcholine; the various subspecificities of these proteins for phosphorylcholine analogues can be accounted for by amino acid changes in the hypervariable regions of the heavy chains
Multi-wavelength Observations of Blazar AO 0235+164 in the 2008-2009 Flaring State
The blazar AO 0235+164 (z = 0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to γ-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the γ-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R_g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus
The One-Loop H^2R^3 and H^2(DH)^2R Terms in the Effective Action
We consider the one-loop B^2h^3 and B^4h amplitudes in type II string theory,
where B is the NS-NS two-form and h the graviton, and expand to lowest order in
alpha'. After subtracting diagrams due to quartic terms in the effective
action, we determine the presence and structure of both an H^2R^3 and
H^2(DH)^2R term. We show that both terms are multiplied by the usual
(t_8t_8\pm{1/8}\epsilon_{10}\epsilon_{10}) factor.Comment: 20 pages, 3 figures; corrected typo
A Bilateral Comparison of Fruit and Vegetable Consumption: United States and Canada
Many public programs promote diets rich in fruits and vegetables based on evidence of the derived health benefits. Still, produce consumption in the United States lags behind other nations, even its most culturally similar neighbor--Canada. This study uses a structural latent variable model to test the role played by quality and health information in explaining observed differences in produce consumption. The Alchian-Allen effect predicts that higher quality, higher absolute margin produce will be exported, suggesting quality may be an important demand factor in importing nations such as Canada. The results show that dietary health information is significant in expanding demands. Quality also promotes fruit consumption in Canada.Alchian-Allen effect, fruit and vegetable trade, health information, latent variable, MIMIC model, produce quality, Food Consumption/Nutrition/Food Safety,
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